In Summary, for those who got the chewing gum:

Benefits in NNT

  • 7% were helped by preventing post-operative ileus
  • 0% were helped by shorter hospital stay
  • 1 in 15 were helped (preventing post-operative ileus)
  • None were helped (shorter hospital stay)

Harms in NNT

  • An unknown number were harmed by chewing gum
  • An unknown number were harmed (from chewing gum)

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Source: Craciunas L, Sajid MS, Ahmed AS. Chewing gum in preventing postoper-ative ileus in women undergoing caesarean section: a systematic review and meta-analysis of randomised controlled trials. BJOG. 2014 Jun;121(7):793-9

Efficacy Endpoints: Post operative ileus, time to flatus, time to defecation, need for enemas, need for antiemetic, length of stay

Harm Endpoints: Not addressed

Narrative: Post-operative ileus (POI) complicates a significant percentage of surgeries. By delaying the normal return to gastrointestinal (GI) function, POI may increase patient discomfort and has been shown to prolong hospitalization by five days, increasing total costs by almost $1 billion1. Surgeons and medical teams have tried numerous pharmacologic and non-pharmacologic interventions for POI. The perfect intervention for reducing POI would be physiologic, effective, safe, and inexpensive. Early reintroduction of diet, although ideal, is not tolerated by some patients. Chewing gum may trigger salivation and the same neurodigestive processes that lead to normal GI function, and thus could represent a viable alternative to early diet reintroduction. Other research has shown gum chewing can reduce time to flatus, time to defecation, length of stay, and the time to tolerate a diet in post-operative gynecologic oncology patients2.

The present study examined the effectiveness of chewing gum to reduce post-caesarian ileus. The authors included seven, randomized-controlled trials encompassing 1,462 patients. Regarding the main outcome, three studies of 1,086 patients showed that chewing gum reduced the rate of post operative ileus by 7% for an NNT of 15. The authors show that the intervention also significantly reduced time to flatus, time to defecation, need for enemas, and need for antiemetics. There was no significant difference in length of stay.

The authors did not assess harms, although these are likely insubstantial. Theoretical harms include choking, dental pain/TMJ dysfunction, and distaste. A separate study on minimally-invasive gynecologic surgery patients demonstrated no related adverse effects3.

Overall, this is a fairly well-performed meta analysis limited by mostly low quality evidence. Given the potential patient-centered benefits and lack of demonstrated or likely harm, we recommend consideration of the intervention, pending more definitive research.

Caveats: Overall, included studies were of mostly low quality. This was limited by a general inability to blind patients to chewing gum, but a number of studies also lacked blinding of observers, and certain trials had incomplete concealment. Given the trials were all performed in the Middle East and Asia, it is unclear if they are externally valid to the Western world.

Additionally, the authors report standardized mean differences for most of the outcomes. Although this allows for combining studies using different outcome measures, it also requires study populations to be similar. Given the heterogeneity in the studies, this may not be true. Heterogeneity was large due to differences in patient populations, specific interventions, variations in diet, and outcome definitions.

A separate meta analysis published in the same journal issue4, demonstrated similar findings. The authors extracted six articles, similarly of low to moderate quality and significant heterogeneity. Zhu et al reported a decreased time to flatus by six hours and time to defecation by seven hours. In contrast to Craciunas et al, this article demonstrated a significant decrease in length of stay by six hours. No significant adverse effects were noted. Although both analyzed randomized controlled trials regarding gum chewing and post-operative ileus, the two articles differed in specifics of search process and statistics, which may account for outcome differences.

Author: Gary Green, MD

Published/Updated: January 6, 2015

  1. The Title Bar

    The title bar is color-coded with our overall recommendation.

    • Green: Benefits outweigh risks.
    • Yellow: Unclear risk/benefit profile.
    • Red: Benefits do not outweigh risks.
    • Black: Obvious harms, no clear benefits.
  2. Tip content...